1. Field of the Invention
The invention relates to a method of hydrating a sponge material for delivery to a body.
2. Brief Description of the Related Art
A large number of diagnostic and interventional procedures involve the percutaneous introduction of instrumentation into a vein or artery. For example, coronary angioplasty, angiography, atherectomy, stenting of arteries, and many other procedures often involve accessing the vasculature through a catheter placed in the femoral artery or other blood vessel. Once the procedure is completed and the catheter or other instrumentation is removed, bleeding from the punctured artery must be controlled.
Traditionally, external pressure is applied to the skin entry site to stem bleeding from a puncture wound in a blood vessel. Pressure is continued until hemostasis has occurred at the puncture site. In some instances, pressure must be applied for a up to an hour or more during which time the patient is uncomfortably immobilized. In addition, a risk of hematoma exists since bleeding from the vessel may continue beneath the skin until sufficient clotting effects hemostasis. Further, external pressure to close the vascular puncture site works best when the vessel is close to the skin surface and may be unsuitable for patients with substantial amounts of subcutaneous adipose tissue since the skin surface may be a considerable distance from the vascular puncture site.
More recently, devices have been proposed to promote hemostasis directly at a site of a vascular puncture. One class of such puncture sealing devices features an intraluminal anchor which is placed within the blood vessel and seals against an inside surface of the vessel puncture. The intraluminal plug may be used in combination with a sealing material positioned on the outside of the blood vessel, such as collagen. Sealing devices of this type are disclosed in U.S. Pat. Nos. 4,852,568; 4,890,612; 5,021,059; and 5,061,274.
Another approach to subcutaneous blood vessel puncture closure involves the delivery of non-absorbable tissue adhesives, such cyanoacrylate, to the perforation site. Such a system is disclosed in U.S. Pat. No. 5,383,899.
The application of an absorbable material such as collagen or a non-absorbable tissue adhesive at the puncture site has several drawbacks including: 1) possible injection of the material into the blood vessel causing thrombosis; 2) a lack of pressure directly on the blood vessel puncture which may allow blood to escape beneath the material plug into the surrounding tissue; and 3) the inability to accurately place the absorbable material plug directly over the puncture site.
The use of an anchor and plug system addresses these problems to some extent but provides other problems including: 1) complex and difficult application; 2) partial occlusion of the blood vessel by the anchor when placed properly; and 3) complete blockage of the blood vessel or a branch of the blood vessel by the anchor if placed improperly. Another problem with the anchor and plug system involves reaccess. Reaccess of a particular blood vessel site sealed with an anchor and plug system is not possible until the anchor has been completely absorbed because the anchor could be dislodged into the blood stream by an attempt to reaccess.
Yet another approach to subcutaneous puncture closure involves the internal suturing of the blood vessel puncture with a specially designed suturing device. However, these suturing devices involve a significant number of steps to perform suturing and require substantial expertise.
Another method of closure for subcutaneous punctures involve the use of sterile sponges, such as Gelfoam. The sponges are prepared in dry sterile sheets which are used as packing material during surgery for control of bleeding. The sponge sheets are left in the surgical site after surgery to stop bleeding and are absorbed by the body in one to six weeks. A number of techniques have used these absorbable sterile sponge materials to plug a biopsy tract to minimize or prevent bleeding. The absorbable sponge provides a mechanical blockage of the tract, encourages clotting, and minimizes bleeding though the biopsy tract. Despite the advantages of using an absorbable sponge to plug a biopsy tract this technique has not achieved widespread use because of difficulty in preparing and delivering the sponge material into the biopsy tract.
One example of a wound closure device using an implantable sponge is described in U.S. Pat. No. 5,388,588. According to this patent, a circular sponge of an absorbable foam material is precut and inserted into a biopsy site by an applicator rod having the sponge positioned on the end. Once the sponge is implanted, the sponge absorbs blood and swells to fill the tract preventing further bleeding at the biopsy site. However, the sponge is difficult to deliver and expands slowly once delivered. In addition, this delivery method can only deliver a sponge of a limited size which provides less local compression than desired and may incompletely fill the target site. Further, bleeding may continue along sections of the biopsy tract where no sponge has been delivered.
In addition, gelatin sponges such as Gelfoam that are delivered in a dry state to a desired target site expand slowly because they soak up fluid slowly. It may take several minutes or longer for a dry sponge to absorb enough fluid to facilitate complete expansion of the sponge at the target site.
Pre-hydration of the sponge (ie before delivery to a target site) with a biocompatible fluid such as water, saline solution, blood or blood product, or any other blood miscible fluid facilitates wetting of some or all of the cell walls of the sponge. The more complete the pre-hydration, the more complete the wetting of the cells.
Pre-hydration can be accomplished by mechanically kneading the sponge fluid or by prolonged soaking in fluid. However, this can be tedious and time consuming, and may not lend itself to many delivery systems. One alternative is to provide the sponge sterile and pre-hydrated within its delivery to soak the sponge after it has been placed within its delivery system.
Accordingly, it would be desirable to provide a method of hydrating a sponge for delivery to a body which addresses the drawbacks of the known systems.
In order to improve the ability and capacity of the sponge material to expand upon delivery, the present invention provides a method of hydrating a sponge material which has the ability to rapidly saturate with blood and correspondingly rapidly expand upon delivery to a bodily site.
According to one aspect of the present invention relates to a method for hydrating a sponge material for delivery to a body includes the steps of placing a dry piece of sponge in a container at a first pressure; introducing a hydrating fluid into the container to hydrate the sponge; changing the pressure within the container between the first pressure and a second pressure; removing at least a portion of the hydrating fluid from the sponge; and delivering the sponge to a bodily site.
In accordance with another aspect of the present invention, a method of hydrating a sponge material for delivery to a body includes the steps of placing a sponge in a container; repeatedly changing a pressure of a hydrating fluid within the container to hydrate the sponge; and delivering the sponge to a bodily site.
For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description, taken in conjunction with accompanying drawings, and its scope will be pointed out in the appending claims.